Multichannel radio system



Jan. 3, 1928. 1,654,920 E. L. CHAFFEE w 1 MULTICHANNEL RADIO SYSTEMFiled Auzlz. 1922 v 71v VENZOR HIS/I TTORNEY Patented Jan. 3, 1928.

UNITED STATES IIOBY LEON Panzer! OFFICE.

Cmm, O I' BELMONT, MASSACHUSETTS, ASSIGNORTOiJOHN' HAYS WORD, .13., 0FGLOUCESTER, IASSAGEUSETT$- xumrcnammr. aanio srs'rmr.

Application fled August 29, 1982. Serial No. 584,958.

This invention relates to systems for the transmission and reception ofradlant energy and has for its object to provide im-- proved methods andmeans for the transmission of intelligence by Hertzian waves whereby amessage may be reliably received with a minimum of interference orblocking; to provide means for receivin a message over a plurality ofchannels havlng different characteristics independently thus eflectuallypreventing blocking by malicious outelders; and to provide methods andmeans for producin from different sources of energy a plura 'ty ofseries of beats of the same frequenc for controlling an indicatingdevice, where y any one of the series of beats may be employed forcontrolling the indicating device. Still other objects of the inventionwill appear from the following description taken in connection with theaccompanyin drawing.

The sing e figure of the drawing shows diagrammatically one form ofreceiving system embodying the invention.

In the drawin there is shown so much of a so-called wireless receivingstem as is necessary to an'understanding o the invention. It isunderstood that the sending equipment (not shown) is adapted to impressupon the ether, a plurahty of continuous waves all modulated atdifierent frequencies but in a similar manner.

- The illustrated system comprises a loop 10 and a second loop 11arranged at right anglies thereto, both loops being positioned at anangle of substantially to the direction from which the radiant ener .isexpected to be received. The 100 10 orms part of a closed circuit 12inclu g an adustable condenser 13 and resonant to apredeterminedfrequency. This frequency w1ll be hereinafterrepresented by the symbol A1.

The circuitof the loop 10 is operatively connected to a three-electrodeelectron device 14 comprising a sealed container having therein a usualheated filament for emitting electrons, a plate 18' upon which theelectrons impinge, and a grid 19 for controlling their passage. The gridis connected to the loop 10 so as to be controlled by electricaloscillations caused to be set up therein by electro-magnetic orso-called Hertzian waves.

The loop 11 forms part of a similar closed circuit 15 which includes anadjustable condenser 16 and is adjusted to be resonant to a secondfrequency A 2 differing from the first-namedfrequenc A 1.- The circuitof the loop 11 is similar y connected to the grid of a second threeelectrode electron device 17 having a usual heated filament, grid and hesecondary winding of each of the transformers 21 and 23 is included inan oscillatory circuit, such as 40 and 41 respectively, each includingmeans for tuning the circuit, such as a variable condenser or the like,to be resonant to the respective modulating frequencies.

Each oscillatory circuit 40 and .41 includes a primary winding of atransformer, v

such as and 51 respectively, the secondary windings of which form partsof closed oscillatory circuits 52 and 53 including adjustable condensers54 and 55 respectively.

The circuit 52 is operativel connected to a three-electrode eiectrondevice 56 and is arranged to act upon its grid 19 to control the outputcircuitof the plate 18 thereof. Similarly, the close circuit 53 isoperatively connected to the g 'd 19 of a corresponding thermionicdevice 7.

The plate circuits of the devices 56 and 57 include respectivelywindings 60 and 61 of a transformer 62. Inductively cou led to thesewindings is a tertiary win in which is included in a resonant circuit 64having, for example, a variable condenser 65 and a winding 66 of acoupling 67.

The coupling 67 is provided with asecondary winding 70 connected incircuit with the id 19 of a thermionic device 71, having a. usual heatedfilament. A tuning condenser 72 may be provided in a conventionalmanner. The output circuit of the device 71 may include a controlleddevice, such as "a telephone receiver 73. The controlled device may,however, take the form of a solenoid or relay to control a movement orfunction of a body such as a. torpedo, boat or other object.

A heterodyne shown conventionally as an alternator 80 and a transformer81 acts on a conductor 82 included in the grid circuits of both devices56 and 57.

Operation of theheterodyne 80 produces 'an alternating electro-motiveforce in the conductor 82 and, in co-operation with the oscillationsinduced in the secondary windings of the transformers and 51, aplurality of series of beats, as will be subsequent 1y set forth.

It is obvious that the tuning condensers 54, and 72 may be omittedwithout seriously affecting the operation of the system.

In the operation of the system described, the sending station isconstructed to impress upon the ether two series of continuous waves ofdifferent radio frequencies. The frequencies will be hereinafterdesignated A 1 and A 2 respectively. The waves are modulated at thesending station by currents of frequencies (B 1 and B 2) less than theirwave frequencies. The receiving loops 10 and 11 and the associatedcircuits 12 and 15 are tuned respectively to the frequencies,-

A 1 and A 2.

The thermionic devices 14 and 17, acting as detectors, (produce in theiroutput circuits superimpose currents having frequencies corresponding tothe modulating frequencies employed at the sending station. The tworesonant circuits 40 and 41, which are tuned respectively to thesemodulating frequencies, transmit currents of substantially thesefrequencies only. The heterodyne 80, 81 is adjusted to produce analternating electromotive force having a fre uency such that it roducesequal heat requencies with modulating frequencies B 1 and B 2. Thesebeats control the devices 56 and 57 respec-' tively, and there areproduced in the output circuits thereof, including the windings 60 and61 of the transformer 62, superimposed currents of this last named beatfrequency. This beat current is induced into the circuit of theindicating device or magnet 73. Circuit 64 is resonant to the beatfrequency. The electron device 71 may act as an amplifier when analternating current device such as a telephone receiver 73 is used or asa rectifier when the device 73 is a solenoid, .or other direct currentdevice.

While an desired frequencies may be employed w ich fulfill the aboveenumerated requirements, I will cite as examples which may be employedfor telegraphic messages the following: 1

A 1; 500,000 cycles per second. t

A 2; 200,000 cycles per second.

B 1; 18,000 cycles per second.

B 2; 20,000 cycles per second.

Heterodyne 19,000 cycles per second.

Beat 1,000 cycles per second. 7

Thus it will e seen'that a message may be transmitted bysuitablymodifying, as by interrupting, or otherwise modulating thecurrents of frequencies, B 1 and B 2, these currents thus acting asso-called carriers. Since two independent carriers are employed,eachproducing independently a beat current, the message appears in theoutput or indicating circuit, even though outside interference or otherdifliculty has rendered one of the channels temporarily inoperative.

If desired, in the use of the system the message may be broken up intoseveral illegible parts, each so chaotic that it cannot be understood.For example, if the message be telegraphic, the dots may be sent overone channel and the dashes over the other. Illegitimate listening inwould not then result in revealing) the true messa e, as neither channelcould e understood a one.

While I have shown and described'one of the forms in which the inventionmay be practiced, and given by way. of example values for the requencieswhich may be employed, it is to be understood that the scope of theinvention is not to be determined thereby, reference being had to theappended claims for that purpose. For example, the modulatingfrequencies, B 1 and B 2, may be equal: in the example cited B l=20,000cycles per second.

What is claimed is:

1. A system for the transmission of intelligence by radiant energy,comprising a plurality of channels for receiving the radiant energyindependently of each other, said channels including a correspondingplurality of receiving devices tuned to frequencies differing from eachother by a predetermined amount, and heterodyne means for producing withoscillations of said frequencies a pluralit of series of beats ofsubstantially equa frequencies.

2. A system for the transmission of intelligence b I plurality 0receiving channels selectively responsive to different portions of saiden ergy, said channels including 1!. correspondmg plurality of receivingcircuits tuned to fre uencies differing from each other by a proetermined amount, heterodyne means or producing with oscillations set 11radiant energy, comprising a said channels a pluralit 0f series of atsof substantially equal requencies, and an indicating device connectedwith saidqchan nels.

8. A system for the transmission 'pf in telligence 'b radiant energy,comprising a pluralit 0 channels for receiving a message m ependentlyof'each other one. plurality of series of waves differing in a frequencycharacteristic, said channels including a corresponding plurality ofreceivin circuits tuned to different frequencies, an

means for producing current of lower frequency from each of said seriesof waves,

heterodyne means for producing with said.

currents a corresponding plurality of series of beats of substantiallyequalfrequencies and an indicating device connected to sai channels andresponsive. tooscillations having the frequency of said beats.

4. In a system for the transmission of a message through the ether, aplurality of channels for inde endently recelving a plurality of series0 waves of different radio frequencies, said channels includingreceiving circuits exposed and responsive to the ether waves and tunedto their different frequencies respectively and means cooperativelyassociated with each of said circuits for producing current of lowerfrequency from the waves received thereby, and heterodyne means forproducing with the respective currents a plurality of series of beats ofsubstantially equal frequency.

5. .In a system for the transmission of a message through the ether, aplurality of channels for independently receiving a message from theether on a plurality of series of waves of different radio frequencies,each of said channels including a receiving circuit arranged to beresponsive to ether waves and tuned to one of said difl'erent wavefrequencies and means cooperatively associated with said circuit forproducing current of lower frequency from the waves received thereby,heterodyne means for producing with said currents a correspondingplurality of series of beats of substantially equal fre:

quencies, and an indicating device connected w1th sald channels.

6. In a system for the-transmission of a message through the ether, aplurality of channels for independently receivin the message from theether on a plurahty of series of waves differing in a frequencycharacteristic, said channels including means for producing currents ofdifferent frequencies from the respective series of waves and receivingcircuits tuned to said different frequencies, means for producing w1thsaid currents a corresponding plurality of series:

of beats of substantially equal frequencies, a circuit selectivelyresponsiveto the frequency of said beats, and an indicating devicecontrolled by said last-mentioned circuit.

7. In a system for the transmission of a message through the ether, aplurality of channels for independently receiving the message from theether on a plurality of series of waves differing in a frequencycharacteristic, said channels including means for producing currents ofdifferent frequencies from the respective series of waves, heterodynemeans for producing with said currents a correspon ing plurality ofseries of beats of substantially equal frequencies an indicating deviceres ons ive to currents of the frequency of ear beats, -.and means forselectively transmitting osc11lat1ons having the ether a and anindicating device responsive to currents of the frequency of said beats.

9. In a system for the transmission of a message through the ether, aplurality of differently tuned channels for independently receiving fromthe ether a plurahty of series of high frequency waves modulated atdifferent secondary frequencies, means in each of said channels fordetecting the en ergy received thereby to produce current of therespective secondary frequency, bet-- erodyne means for producing withthe currents from said channels a corresponding plurality of series ofbeats of substantially equal frequencies, said means including a networkindependently coupled to .each of said channels, and an indicatingdevice connected with said network.

10. In a system for the transmission o'fla message through the ether, apluralit '-'of channels for lndependently receiving rom ondaryfrequencies, means in each of the channels; for detecting the energy"received; thereby to produce current of the respective secondaryfrequency, receiving circuits in the ether a plurality of series ofhigh-ire- 1 quency waves modulated at diiferent'sec the channels tunedto the secondary frequencies respectively, heterodyne meansfor producingwith the currents from said channels a corresponding plurality of seriesof,

beats of substantially equal frequencies, and

an indicating device connected with the channels.

' 11. Ina system for the transmissionof'a messagethrough the ether, aplurality of channels. for independently receiving from plurality ofseries of waves of dlfierent radio frequencies, each modulatedat asecondary frequency, circuits responsive y to the waves included in saidchannels respectively and tuned to said different radio frequencies,means cooperativel with each of said circuits for etecting the energyreceived thereby to roduce' current of the corresponding secon ary freuency, heterodyne means for producing w1th the currents from saidchannels a corresponding plurality of series of beats of substantially 7equal frequencies, and an indicating device connected to said producingmeans and said channels.

associated 12. In a system for the transmission of a message through theether, a pluralityt of cm channels for inde endently receiving the ethera plura ity of. series of waves of different wave frequencies modulatedat different secondary frequencies respectively, a plurality of circuitsincluded in each of said channels and tuned respectively to one of saidwave frequencies and one of said sec ondary frequencies, means in eachof said channels beween said circuits for detecting the energy receivedthereby to produce current of the corresponding secondar frequency,heterodyne means for pro ucing with the currents from said channels acorrespondin plurality. of series of beats of substantia y equalfrequencies, and an indicating devices-connected to said producing meansand said channels.

, 13. In a system for the transmission of a message through the ether ona plurality of substantially equal fre uencies.

j 14. In a system for t e transmission of a message through the ether ona plurality of 'serigw of waves, a receiving arrangement comprisin aplurality of independent channelsiinclu ing difierently. tuned circuits,.an i indicating device andimeans for. transmitt' current from saidchannels to the indicatingdevice, said means comprising a heterodyne"for convertin currents from said channelsainto audio requency currentsof substantially equal frequencies'and an oscillatory circuit tuned to asaid last-mentioned frequency.

15. A method of communicating al'mes:

edge by radiant energy which'eonsists in transmitting apluralit ofseries of high fre uency wavesmod ated in accordance .wit the message,receiving said pluralit of series of waves in separate rece1v1n cannels, producing in said receivin c annels from said plurality ofseries 0 waves a correspondin plurality of series of currents ofdifierentfrequencies respectively, heterodyning said currents toproducetherefrom a plurality of series of beats ofsubstantially equalfrequencies and controlling a single indicating device by said pluralityof series of beats. v I

16. A method of communication by radiant energy which consists-intransmitting a plurality of series ofhigh fr uency waves of difierentwave frequencies aving periodic variations of different frequenciesrespectively and all modulated in accordance with the message, receivingthe pluralit of series of waves indifierent receiving 0 annels,detecting the series of waves in the respective receiving channels toproduce currents having the frequencies of the variations respectively,heterodyning said currents to produce a plurality of series of beats ofsubstantially equal frequencies, and controlling a single 1ndicatingdevice by said of series of beats.

17 T e method of communicating a message by radiant energy whichconsists in transmitting two series of high fnequenc waves, eachmodulated in accordance with the entire message, receivin the two seriesofwaves 1n difierently tune receiving channels, roducing in saidchannels two currents modu ated in accordance with the modulations ofthetransmitted waves, heterodyning the currents to produce two series'of beats of substantially equal frequencies and impressing both of saidseries of beats on a common indicatin device.

'In testimony-w ereof I hereunto afiixed my signatures nmoagr LEONCHAFFEE.

